Dragline excavator



June 2, 1936. M. L. FYKsE DRAGLINE EXCAVATOR Filed Aug. 30, 1954 WQ mm w Z7 Mm Mm mw mv UM, lll a J b Y B Q b fh J EN A TTORNE YS.

Patented June 2, 1936 DRAGLINE EXCAVATOR Mitchell L. Fykse, South Milwaukee, Wis., as-

signor to Bucyrus-Erie Company,

'South Milwaukee, Wis., a corporation of Delaware Application August 30,

5 Claims.

My invention relates primarily to dragline excavators.

Dragline excavators are well known in the art. They consist of a main platform carrying the actuating machinery, there being -a boom, swingable in a vertical plane, carried at one end of said platform. The outer point of the boom carries a vertical sheave, either pivoted in the boom, with no provision for side swing, or else pivoted in a yoke, which in turn depends from a substantially horizontal axis in the vertical plane of the boom. About this sheave is reeved the hoist-rope, which serves to raise and lower the digging bucket.

Neither of the older constructions, as outlined above, allows the resultant of the pull of the hoist-rope on the sheave, and of the boom-suspension-cables on the end of the boom to pass through an unvarying point on the boom, regardless of the distance of the bucket from the main platform, and regardless of the inclination of the boom, and regardless of the working distance of the bucket off-side lof the vertical plane through the boom. This failure necessarily introduces both bending stresses and torsional stresses in the boom. These stresses and torsions are eliminated in my invention.

Furthermore the use of a longitudinal pivot for the hoist sheave requires the inclusion of several heavy diaphragms across the boom, to hold the bearings for said longitudinal pivot, thereby adding to the dead weight of the boom.

In my invention, the only pin in contact with the boom is a transverse one, which requires no such heavy auxiliary diaphragms for its support, as it is held directly by the main boom members. I therefore have .thus reduced the necessary weight of the boom.

Also, the action of my sheave-yoke, in swinging fore and aft in a vertical plane and/or to either side, in response to the lead of the hoist cable, when the bucket is at varying positions with respect to the machine, retains the desirable characteristic of having the resultant load on my sheave pin always pass through the center of the supporting pin on the boom, said center point being on the neutral axis of the boom. And, inasmuch as my boom suspension is also brought to an axis passing through this same point, there is no bending moment imposed upon the boom, and the torsional loading on the boom is completely eliminated.

In addition to my principal objects, as enumerated above, I have worked out a number of 1934, Serial No. '742,053

novel and useful details, which will be readily evident as the description progresses.

My invention consists in the novel parts, `and in the combinations and arrangements thereof, which are defined in the appended claims; and of which one embodiment is exemplified in vthe accompanying drawing, which is hereinafter particularly described and explained.

Throughout the description, the same reference number is applied to the Ysame member or to similar members. y

Referring to the drawing, it will be yseen thatv Figure l shows a side elevation of my invention,v part being i-n section, as indicated by line I-I, in Figure 2. v Y

Figure 2 shows a vertical section of my invention, as indicated by the line 2 2, in Figure 1.

Figure 3 is a simplified representation of a dragline embodying my invention.

It will be seen that the boomv I0 comprises two side plates II, which are stiffened against lateral bending by the angle pieces I2, which are located on the upper side of the booml.

At the upper end of the boom, each side plate II carries on its Youter face afixed bearing I3, which carries non-rotatably the bearing-blockpin I4, the said pin being transverse to the boom.

VRotatably mounted at the outer ends of this bearing-block pin I4, and symmetrically positioned with respect to the vertical plane through the neutral axis of the boom, are the boom-suspension sheaves I5, of which there may be more than are shown, if the boom-suspension cable is to be many-part.

Between the two side-plates II of the boom, and Vcentrally spaced, with respect to the sideplat'es, by the spacers or sleeves I6, there 'is a bearing-block Il, rotatably carried by the `vpin III. Integral Vwith the bearing block Il .is a pair of axially al'in'ed ltrunnion's I8. The axis -of the trunnions 4I8 and the axis of the Ipin 'Il Yperpendicularly bisect each other, the point of bisection being on the neutral axis of the boom. The axis of the trunnions is therefore always in a vertical plane through the Said neutral axis.

The trunnions i8 carry, depending therefrom and mounted for swinging thereon, a yoke I9, which supports at its lower end a hoist-sheavepin 20, upon which the hoist-sheave 2| is rotatably carried.

The hoist-sheave-pin 20 also supports rotatably a depending bucket 22, to which the dead end of the hoist-rope 23 is secured.

As the hoist-sheave-pin 20 is always at right angles to the axis of the trunnions I8, which latr2.1.. e.. ,i

ter is always at right angles to the axis of the bearing-block-pin I4, and as the rotation of the yoke I9 about either or both axes is preferably free, it is obvious that the hoist-sheave-pin 20 is not constrained to remain parallel to the bearing-block-pin I4, but may take a position such that the hoist-sheave 2| is free to set itself in the plane of the leads of the hoist-ropes 23, what-Y ever may be the distance that theV bucket 24 is off-side of the center-line of the main machine.

Also, because of this complete freedom of po sitioning of the yoke I9 and the hoist-sheave 2I, it is obvious that the center line of the yokeIS is quite freeto set itself in the line of the resultant of all the forces acting onV the yoke; so that there is perfect delivery of the hoist-rope to the hoist-sheave, Whatever may be the position of the bucket. i

The boom-suspension cables 25 are reeved about the sheaves I5.

Furthermore, as the forces on the boompoint-which are the weight of the yoke and sheave, the resultant of the tensions in the vari- Vous reaches of the hoist-rope *in any operating position thereof, and the resultant of the boomsuspension forces-al1 pass through the same point, viz., the point 26, which is the intersection of the centerline of the bearing-block-pin I4 with the center line of the trunnions I8, it is obvious that the Yhoorn will act merely as a column; that is, the loading, however departing from kthe vertical, will introduce merely compressional stresses',V but no bending, into the boom.

Furthermore, because of the perfect freedom of the yoke to set itself in the line of the resultant of all forces uponit evenjwhen the bucket is off-side, there can be vno torsional stresses imposed upon the boom bythe load. Y

Even if the axis of the trunnions I8 were, for anyreason, such as constructional considerations, slightly' oiset from exact intersection with the axis of pin I4) there would still be no bending ample, still in the central vertical plane of the boom, but passing a short distance above the axis of pin I4) there would still be no bending moment introduced into the boom, and only a negligible torsion, when the bucket is olf-side.- Having now described and illustrated one form of my invention, I wish it to be understood that my invention is not to be limited to the'specic form or arrangement of parts hereinbefore described, except in so far as such limitations are specified 'in the appendedclaims.

I claim: Y 1."In a dragline excavator, the combination of: a main frame; a boom extending therefrom; a transverse horizontal pin at the outer end' of the boom; boom-suspension sheaves, mounted on said pin; a pair of trunnions perpendicular to said pin and pivotally mounted thereon; a yoke pivotally mounted on the trunnions, and depending therefrom; a transverse pin in the yoke; a hoist-sheave suspension sheaves, having their axes in substantial alignment With the transverse axis ofthe universal joint; a hoist-rope, extending from the main frame directly around the hoist-sheave, and thence toY an operative association With the bucket; and a boom-suspension-cable, reeved about the boom-suspension sheaves.

3. In a dragline excavator, the combination of: a main frame; aboom extendingV therefrom; a

transverse horizontal pin at the-outer end of the boom; boom-suspension sheaves, mounted on said pin; a pair of trunnions perpendicular to said pin,

andpivotally mounted thereon, and having its trunnion-axis intersect the axis of the pin; a-yoke pivotally mounted on the trunnions, and depending therefrom; a transverse pin in they yoke; a` hoist-sheave pivoted thereon; a hoist-rope, ex-

tending from the main frame directlyaround the hoist-sheave, and thence to an operative association with the bucket; and aiboom-suspensioncable, reeved about the boom-suspension sheaves. Y

4. In a dragline excavator, the combination of V:A

a main frame; a boom extendingtherefrom; a hoist-sheave; means suspending the hoist-sheave from the' outer end of the boom forf sidewise swinging Vmovement.' means suspending the sheave for Vfore-and-aft swinging movement; boom-suspension means; and a hoist-rope, ex-

tending from the main frame directly around thev hoist-sheave, and thence-to an operative association with the bucket; the various elements being so positioned that the Vliney of resultant tension in the hoist-rope, the line of resultant tension in the boom-suspension means, and the line of compression of the boom will substantially intersect.

5. `In a dragline excavator, the combination of: a main frame; a boom extending therefrom; a universal' joint at theV outer end of the boom; sheave-supporting means, depending from said universal joint; a sole hoist-sheave swiveled in said sheave-supporting means, below thepoint of suspension thereof; boom-suspension means, secured to the boomA at points in substantial alignment with the transverse axis of the universal joint; and a hoist-rope passing directly rvfrom-the main frame over the hoist-sheave, and thence MITCHELL L.

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